About Raindex

Raindex is Raindex: Rain Totals & Gauge, an iPhone app that measures how much rain fell at specific places in the United States. It is built and run by Kirill Proskurin, an independent developer, not a weather company.

What it uses

Observed rainfall comes from NOAA’s Multi-Radar Multi-Sensor system (MRMS), which merges the national weather-radar network with rain-gauge observations onto a 1 km grid. Forecasts come from the National Weather Service NDFD. Where this website cites 30-year averages it uses the NOAA NCEI 1991–2020 U.S. Climate Normals. All of it is public U.S. government data. NOAA publishes it; NOAA does not endorse this site or this app.

What it deliberately does not claim

• No accuracy percentage. The quality fields published with MRMS describe radar conditions, not the probability that a number at one property is correct. Presenting one as the other would be the most expensive kind of wrong.
• No distance to the nearest physical gauge. The data does not contain it. Readings are labelled by provenance instead: gauge-adjusted, radar only, or provisional.
• No snow totals. Radar performs materially worse on frozen precipitation. Snow appears only as liquid equivalent, without a quality claim.
• Not a warning service. Official flood and severe-weather warnings come from the National Weather Service. Raindex measures; it does not warn.

Contact

Corrections, questions and feature requests: support@raindex.app. If a number here looks wrong, say so — that is the single most useful message this project can receive.